The function as you've written it, using only static x,y values, isn't really doing math since you're not actually doing any computation. Something like moveTo(getX()+x,getY()+y) might. But then you've already got a move(x,y) command if you want to move the turtle relative to its current position, so that kind of trick might be more appropriate for moving UI elements.

I've got to believe that's correct, because otherwise it would mean I just have to tell my kids to code their UI elements rather than using design mode in order to score big points.